Message may not get saved into imapsql

[majkrzak]

It happen me few times, that message did not get into the imapsql mailbox.
Delivery succeeded and not errors were reported in log.

I can see, those messages being saved in /data/messages directory as 9 copies.

[RadimEZ]

Had this issue myself multiple times as well, but failed to reproduce for a while using newer Go releases. The reason seemed to be a lock race when saving the message to the IMAP storage backend while the mail is still being sent and resides in the outbound queue. My mail client shows an error saving the element. After retrying manually enough time has passed. Those operations don't play well together in parallel.